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| United States Patent |
5,256,190
|
|
Barth
|
October 26, 1993
|
Universal chemical system for offset printing
Abstract
The present invention discloses a universal chemical system for offset
printing comprising a plate coating, a fountain concentrate solution, an
alcohol replacement solution, a roller coating, and a plate wash. The
system uses the same types of chemicals throughout to achieve a system
compatible throughout. The plate coating comprises deionized water, citric
acid, sodium phosphate dibasic, gum arabic, magnesium nitrate solution,
glycerine, and propyl alcohol. The fountain concentrate solution contains
water, citric acid, sodium citrate, sodium phosphate dibasic, sodium
benzoate, gum arabic, glycerine, ethyl hexandiol, and erio green B supra.
The alcohol replacement solution contains deionized water, diethylene
glycol, propasol P, glycerine, and dowanol PM. The roller coating contains
deionized water, citric acid, disodium phosphate, gum arabic, glycerine,
and propyl alcohol. The plate wash contains water, citric acid, dowanol
EB, dowanol PM, maphos 8135, phosphoric acid, and erio glaucine a supra.
| Inventors:
|
Barth; Thomas M. (109 Chiroc Rd., Hendersonville, TN 37075)
|
| Appl. No.:
|
852289 |
| Filed:
|
March 16, 1992 |
| Current U.S. Class: |
106/2; 101/148; 101/451; 101/465; 101/466 |
| Intern'l Class: |
C09K 003/18; B41N 031/08 |
| Field of Search: |
106/2
101/451,148,465,466
|
References Cited
U.S. Patent Documents
| 4030417 | Jun., 1977 | Lipovac | 106/2.
|
| 4238279 | Dec., 1980 | Tsubai et al. | 106/2.
|
| 4748098 | May., 1988 | Schell | 106/2.
|
| 4764213 | Aug., 1988 | Gventer | 106/25.
|
| 4798627 | Jan., 1989 | Schmitt et al. | 106/14.
|
Primary Examiner: Klemanski; Helene
Attorney, Agent or Firm: Lanquist, Jr.; Edward D., Patterson; Mark J., Waddey, Jr.; I. C.
Claims
We claim:
1. A universal chemical system for offset printing comprising:
a. a plate coating comprising deionized water, citric acid, disodium
phosphate, gum arabic, magnesium nitrate solution, glycerine, wherein said
glycerine is more concentrated than said gum arabic by 18-45 percent, and
propyl alcohol;
b. a fountain concentrate solution comprising water, citric acid, sodium
citrate, disodium phosphate, sodium benzoate, gum arabic, glycerine,
2-ethyl-1,3-hexandiol and a green dye;
c. an alcohol replacement solution comprising deionized water, diethylene
glycol, glycol, glycerine, and propylene glycol methyl ether;
d. a roller coating comprising deionized water, citric acid, disodium
phosphate, gum arabic, glycerine, and propyl alcohol; and
e. a plate wash comprising water, citric acid, propylene glycol, propylene
glycol methyl ether, a surfactant, phosphoric acid, and a glaucine dye.
2. A plate coating comprising:
a. deionized water;
b. citric acid;
c. disodium phosphate;
d. gum arabic;
e. magnesium nitrate solution;
f. glycerine, wherein said glycerine is more concentrated than said gum
arabic by 18-45 percent; and
g. propyl alcohol.
3. A fountain concentrate solution created by the method comprising the
steps of:
a. mixing water, citric acid, sodium citrate, disodium phosphate, and
sodium benzoate to form a solution; and
b. adding gum arabic, glycerine, 2-ethy-1,3-hexandiol, and a green dye to
said solution.
4. An alcohol replacement solution comprising:
a. deionized water;
b. diethylene glycol;
c. gycol;
d. glycerine; and
e. propylene glycol methyl ether.
5. A roller coating created by the steps comprising:
a. mixing deionized water, citric acid, and disodium phosphate to form a
solution; and
b. adding gum arabic, glycerine, and propyl alcohol to said solution.
6. A plate wash created by the steps comprising:
a. mixing water and citric acid to form a solution; and
b. adding propylene glycol, propylene glycol methyl ether, a surfactant,
phosphoric acid, and a glaucine dye;
c. mixing said solution and said addition until dissolved.
7. A plate coating for graphic arts printing press comprising a mixture of:
a. deionized water;
b. citric acid;
c. disodium phosphate;
d. gum arabic;
e. magnesium nitrate solution;
f. glycerine wherein said glycerine is more concentrated than said gum
arabic by 18-45 percent; and
g. propyl alcohol.
Description
BACKGROUND OF THE INVENTION
In the past, every chemical that has been designed for use in the graphic
arts offset printing industry, was created to do a specific job. However,
chemicals were not designed to support other chemicals used in conjunction
with the printing press. When the graphic arts industry and its chemical
producers were forced to change to a cleaner, lower volatile organic
compounds (V.O.C.) product line, the chosen chemicals were actually in
many respects incompatible and were interfering with the functioning of
each another thereby, losing the objective of offset printing.
The first objective of chemicals in offset printing is to assist in and
enhance the use of water to protect the non-image area of a printing
plate. Water alone does not have this capability because of the abrasions
that occur in the printing process on the metal used to carry the ink to
the paper. When wear takes place, the metal must be recoated with a
hydrophilic surface to allow the water to be attracted to the non-image
area and not allow the ink to adhere first. In the printing industry, this
is referred to as etching and counter-etching of the non-image area.
The chemical companies prior art approach to this problem was to use an
acid and a hydrophilic substance (gum arabic), along with a salt to
emulsify the acid and gum to be carried in the water to perform the
counter-etch procedure. This product is referred to as "etch" or, more
widely, as a "fountain solution". Regardless of the type of acid or salt
being used, the industry has based the amount of acid in the water on a pH
reading to achieve a level of acid in the water that is strong enough to
turn the gum arabic into an acidity sufficient to adhere to the non-image
area. The concern is that if the pH is not below 4.5, the gum arabic will
not perform in adhering to the plate, and if the pH reading is below 3.5,
the acid will overpower the gum and will not allow the gum to adhere.
In almost every prior art use of a fountain solution, the amount of gum
arabic in the formula will not exceed 1.0 to 1.5 ounces of gum per gallon
of water used on a printing press. The reason for this mixture is that
there reaches a point where gum arabic is so prevalent in a solution that,
depending on the pH reading of the water, it will reach an uncontrollable
state and will create unwelcome results in other areas on the printing
press.
When the printing industry introduced better mechanical devices to improve
the distribution of water to a printing plate, there became a need for a
wetting agent to be added to the water to increase its flow and
wetability. Isopropyl alcohol (IPA) was used to reduce the surface tension
of water and also aid in the cleaning of the surface of the plate with a
high evaporation solvent-based chemical. Unfortunately, by using IPA, the
printer increased by approximately 50% or more the V.O.C. consumption and
also created highly flammable chemistry. Also, there are other undesirable
side effects inherent in chemicals using alcohol. Because of its highly
volatile nature along with its extremely quick evaporation rate, alcohol
made printing plants a larger producer of volatile organic compounds
(V.O.C.) that enter into the atmosphere. Further, alcohol has a tendency
to mix other chemicals of an alien nature into harmonizing water. Alcohol
tended to break down the ink which can cause major incompatibilities.
Further, the addition of other types of chemicals used in the printing
process caused the interruption of chemical performance and interruption
of performance of substitutes.
When the printing industry was required to use chemicals which produced
lower levels of V.O.C. into the atmosphere and which were less dangerous
to employees, the chemical industry decided to substitute chemicals to
have the same characteristics as one chemical with several different
chemicals of a lower V.O.C. readout and a lower volume usage. Alcohol is
an absolute chemical and allows tremendous latitude because of the effects
it has with its dosages and its capability of blending other chemicals
together. The chemical companies also focused on the replacement of
alcohol, really not paying any attention to the effects the other
chemicals were having on the printing press and what effect alcohol was
having in the grand scheme of things. By still using the same formulas
incorporating acid, salt, and gum arabic, they only created a fourth
chemical rather than looking at the effects of their past chemicals and
how solvents based on glycol and surfactants would affect acid, gum, and
salts.
Because there are other chemicals regularly used in a printing press, how
these substitute chemicals affect the performance of acid, gum, and salts,
must be considered. If any particular chemical interrupts the etching
process of the printing plate created by the acid, gum, or salt, the
process is broken and the performance ruined.
In the past, the art has only looked at one chemical at a time and never
looked at other chemicals that were being used and created. Therefore, no
consideration was given to how each of the chemicals used in the process
were or were not supporting or interfering with the functioning of
another. For example, alcohol was only one among several chemicals used in
the printing process, but it has the capability of blending and mildly
overpowering the other chemicals that enter the water system.
In typical past usage, there have been eleven categories of chemicals used
in an offset press: (1) fountain solution; (2) additives or replacements
for alcohol; (3) plate cleaners; (4) roller washes; (5) blanket washes;
(6) chrome roller cleaners; (7) metering roller cleaners; (8) storage gum;
(9) roller deglazers; (10) blanket conditioners; and (11) anti-skin spray
for the ink. In the past, each of these categories is been formulated
independently with specific chemicals designed to do a specific job, with
little or no regard to compatibility or joint functionality.
Fountain solutions usually comprise an acid base, desensitizing salts, and
gum arabic and are intended to counter-etch the non-image area of a
printing plate. This causes normal fountain solutions to accelerate a
chemical reaction of low level bonding at a more frequent rate. This is
why many fountain solutions work better in some areas than in others
because they depend on the types of salts and acids that are incorporated.
Further, the surface may not accept the lower level of etching of certain
types of acids and salts that are not compatible with its chemical makeup.
In most cases, the fountain solution replacements are designed having a
counter-etching formula and a replacement for alcohol which have a solvent
subtracting base which are extremely vulnerable to failure. Ink is very
sensitive to solvents and acid and once a chemical is pushed beyond the
balance of the water and ink, the ink's identity is destroyed.
Alcohol replacements are designed to reduce surface tension of the water
and most are solvent-based to specifically remove ink from the non-image
area.
All plate cleaners are designed for maintenance of the off-set printing
plate. Plate cleaners are used to remove oxidation, desensitize the
non-image area for scratches, and to replace any hydrophilic chemicals on
the non-image area of the offset plate. Most plate cleaners are made of
acids, desensitizing salts, gum arabics, and surfactants. The off-set
printing plate contains a light film of hydrophilic chemical. During use,
the non-image area is vulnerable to being scratched or oxidized. Further,
the film can be exposed to grease or oxidation. Either of these factors
can interrupt the process. The performance of a printing plate is
determined in the non-image area, which carries water, and in the
image-area, which carries ink. When the non-image area is scratched or
oxidized, the ink begins to adhere to the areas that are to remain clean
of ink. In most cases, the chemicals in the water solution which are to
maintain this balance are not strong enough to etch and to replace the
hydrophilic surface in the problem area. A very strong chemical must be
used to restore the plate to its original condition. In the past, printers
have approached this problem with the theory of a single type of solution
to resolve the entire problem. These cleaners are made with an acid base
along with several desensitizing solvents in a surfactant or mild solvent.
These are inadequate because the chemicals in the cleaner are most likely
different from those in the water solution. The cleaner that was applied
is not supportive of the water and thereby causes the cleaner coating to
be worn off or powered away, thereby exposing the problem area. Repeated
attempts to desensitize the area actually worsened the problem by reducing
the effect and completely destroying the normal function of the etching
chemicals.
Roller washers are designed to remove ink from the inker units on an
off-set press. Roller washes have a solvent base which are made to break
down and flush resins from the surface to which they are bonded.
The purpose of roller and blanket washes is to remove ink from any and all
areas of the printing press. The problem with the typical prior art wash
is that they sometimes have the same type of surfactants that are present
in the developer used on an offset printing plate. This creates a fine
residue of wash remaining on the ink rollers after a wash up. When the
press is re-inked and begins to produce the residue, it leeches out of the
ink and onto the printing plate. The fine residue causes the plate to
react to the solvents and to continue to develop and to interfere with the
balance of ink and water. Consequently, the plate begins to take ink in
the non-imaging area. Further, the blanket wash is used on the plate to
clean dirt and unwanted particles from the surface. This creates the small
amounts of blanket wash beginning to appear in the wash unit from the
result of mixing with water on the printing plate. Again, the balance is
interrupted because the chemicals are not compatible with the water and
therefore interrupt the chemical balance.
Chrome roller cleaners are designed to remove oxidation metals that would
form on the chrome water distribution rollers in an offset printing press.
When the rollers are cleaned, then it is up to the pressman to apply a
layer of eight degrees to fourteen degrees of baume gum to the rollers, to
try to make them repel ink from the roller. When the ink adheres to the
chrome roller, the it cannot distribute the proper amount of water to the
other rollers in the water unit.
Metering roller cleaners were designed to remove ink build-up on the
metering roller in the water unit of the printing press. The metering
roller is used to squeeze the water off the chrome water pan roller. By
adjusting the metering roller, one is able to control the proper flow of
water. When the ink adheres to the chrome water roller, it is then
transferred to the rubber metering roller. As a result the control of
water is interrupted and becomes more difficult. In the printing industry,
this is referred to as a "feedback". When the metering roller is loaded up
with ink, the metering roller cleaner is used to remove the ink.
Blanket washes are designed to remove ink and particles from the off-set
blanket on a printing press and to perform some revitalization of the
rubber.
Storage gums were designed to protect a printing plate when stored for
reuse in for reprinting of a specific job. The protection of the plate is
to insure that the non-image area remains hydrophilic.
Blanket conditioners were designed to remove glaze that would form over a
period of time on a press blanket, from the fountain solution blending
with the residue of paper coating. Blanket conditioners were also intended
to attempt to replace the plasticizers in the blanket that would be
removed by numerous applications of blanket washes.
Anti-skin sprays for ink were designed to prevent ink from oxidizing or
forming a dry layer of ink in the ink fountain of an offset printing
press. The anti-skin spray was also used to retard the drawing of ink
which occurs in the ink roller.
When chemicals are present on a printing press and are applied to a
particular area to cure a problem or perform a major function in
production, at some point, they must interfere with each other. Chemical
molecules will remain on the printing press until they are physically
removed. If they are not removed by human hands, they will be carried from
the press to the printed material. In the printed material, the molecules
will either be consumed by the ink and transferred to the paper by the
off-set blanket, or be consumed by the water and blended into the ink to
be transmitted from the non-image area of the plate to the blanket and
then to the paper. But regardless, the chemical molecules are interfacing
with a carrier, whether the ink or water. A trace of these molecules will
show up somewhere and if the chemicals do not work compatibly or
complement each other, there will be a failure.
Accordingly, what is needed is a universal chemical system for offset
printing which is allows chemical products in the printing press to
support each other and enhance each others performance. This needed system
must allow the chemical washes, additives, and cleaners to support each
other as they are used to perform their separate tasks but not interfere
with one another when they come into contact in various parts of the
procedure. Further, this chemical system must not produce unsafe levels of
V.O.C.'s in the press room or add to the expense of the process.
SUMMARY OF THE INVENTION
The present universal chemical system for offset art printing is based on a
family of chemicals designed to work together and complement and enhance
each other in all areas of the press. Each product of the system is made
from like chemicals which support each other and function in a manner
similar to the other products of the system. To accomplish this, each of
the various product compounds used in the present system formulated from
gum arabic and glycerine, in novel ranges which enhance
inter-functionality. A coating of glycerine and gum arabic is transmitted
to the plate in water.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The universal system of the present invention comprises a plate coating,
fountain concentrate, an alcohol replacement, a roller coating, plate
wash, and a compensator solution.
The fountain solution part of the system starts with a unique blend of
glycerine and gum arabic that forms a completely new surface coating that
adheres to the non-image area of the offset plate. This allows the plate
to perform beyond its normal capability. The glycerine and gum arabic coat
adheres to the non-image area in such a way that it draws and holds more
water than the normal prior art fountain solutions.
The alcohol replacement portion of the system reduces surface tension of
water molecules containing the fountain solution prior to coating the
plate before grease and other unwanted materials bond to the plate. This
enables the fountain solution to coat the plate without interference from
foreign chemicals.
The other solutions work together to clean, desensitize and repair the
surface of the non-image area of the plate. Because the plate wash has the
same solvent base as other component solutions of the system, it removes
the resin and metal deposits from the surface. Using the same types of
desensitizing salts and acids present in the fountain concentrate enables
the plate to accept the ingredients of the glycerine and gum arabic coat.
By applying a coating to the prepared surface with the plate coating
solution, the repaired surface comprises essentially the same chemicals
used in the coating that takes place with the water solution. Therefore,
the maintenance chemicals are supported by the chemicals used in water. If
the plate wash or plate coating enter into the water from over usage, they
do not interrupt the water chemistry but actually enhance it.
The roller coating and plate wash components of the universal system use
the same solvents which are used throughout the system. They remove all
the oxidation material on the chrome surface to prepare the metal for the
roller coating. After the chrome is cleaned, the roller coating is applied
to the chrome rollers. When this glycerine/gum arabic coat film adheres to
the chrome, it creates a new surface that makes the chrome roller perform
at a higher level than before. Because the roller coating uses the same
chemicals as other portions of the system, it is replaced on a constant
basis while the water flows through the water unit and continues to
replace any surface that may be removed from a breakdown. Because the
chrome rollers are being treated just as the metal of the printing press
plate, there is a consistent and perpetual coating being applied which the
printing press is producing. There is no longer a concern for feedback to
the rubber metering roller because it is not capable of adhering to any
metal roller. This then eliminates the need for metering roller cleaners.
The plate wash used in the present universal system interfaces with the
chemicals in the water tank. The plate wash has no surfactants and has the
proper solvents to prevent a residue from forming after usage. The plate
wash is designed to be completely soluble in water and will not, when
entering the water, destroy the balance. Instead, it will actually enhance
the chemicals and fortify their roles.
The ratio of gum arabic to glycerine is critical in order to achieve the
proper coating of the printing plate. The glycerine must be stronger than
the gum by a range of 18-45 percent. In the preferred embodiment,
glycerine is 23-27% more concentrated than the gum arabic. To achieve this
in the preferred embodiment, glycerine is more concentrated that gum
arabic by 0.41 to 1 ounces.
The solvent percentage of the formula is based on the water and mechanical
conditions which can deviate from press to press and from printer to
printer. The proportion of the coating solvent is dependent on the amount
of glycol needed to effectively transmit the water to the plate. In some
circumstances the mechanical part of the water system may be neglected,
such as where the roller that transfers the water may be worn or out of
specification range. By adding glycol, the water surface tension is
reduced and a solvent-based water to be absorbed by the coating to
maximize performance of the non-image area is created. In the worse case
scenario, the solvents dissolved in the water may have to aid the coating
to protect the non-image area by not allowing the imperfection from the
ink to adhere to the coating.
In the preferred embodiment, the volume of solvents in ounces in a gallon
of water must be in the range of a low of 1.37 to a high of 4.426 ounces
to replace alcohol. Thus in a preferred embodiment, 2.78 fluid ounces of
solvent is used per gallon of water. This solvent can consist of any
glycol for the purpose of reducing surface tension of the water. In the
preferred embodiment, the minimum coating in ounces to a gallon of water
is 2.3I49 whereas the maximum is 5.55. In a preferred embodiment, 4.76
ounces of coating is used to one gallon of water.
To make a preferred embodiment of the alcohol replacement solution, the
following percentages of chemicals are used:
______________________________________
CHEMICAL POUNDS OUNCES
______________________________________
DEIONIZED WATER 106 1
DIETHYLENE GLYCOL 81 2
GLYCOL (such as PROPASOL p)
52 12
GLYCERINE 152 12
PROPYLENE GLYCOL METHYL
101 6
ETHER (such as DOWANOL PM)
NEOLAN YELLOW DYE *
______________________________________
*1.36 grams
To make a preferred embodiment of the fountain concentrate, the following
chemicals and percentages are used:
______________________________________
CHEMICAL POUNDS OUNCES
______________________________________
WATER (120.3 GALLONS)
1001 1
CITRIC ACID 31 10
SODIUM CITRATE 31 10
DISODIUM PHOSPHATE 3 6
SODIUM BENZOATE 4 8
Dissolve, then add:
14 Be' GUM ARABIC (110.2
1015 0
GALLONS)
GLYCERINE 657 14
2-ETHYL-1,3-HEXANEDIOL
4 8
SURFACTANT (such as MAPHOS
4 8
8135)
ERIO GREEN B SUPRA Dye
*
______________________________________
*4.88 grams
To make a complete solution the following percent by weight is used:
______________________________________
CHEMICAL POUNDS OUNCES
______________________________________
DEIONIZED WATER (63.4 gallons)
527 13
CITRIC ACID 12 10
SODIUM CITRATE 12 10
DISODIUM PHOSPHATE 1 6
SODIUM BENZOATE 1 9
Dissolve solids then add:
14 Be' GUM ARABIC (37.7 gallons)
346 15
GLYCERINE 96% TECH GRADE
498 5
2-ETHYL-1,3-HEXANEDIOL
1 9
MAPHOS 8135 1 13
DIETHYLENE GLYCOL 145 3
PROPASOL P 94 7
Next, slowly add into the vortex
of the mixing solution:
DOWANOL PM 181 7
ERIO GREEN B SUPRA *
______________________________________
*1.68 grams
The compensator solution is produced by mixing:
______________________________________
CHEMICAL POUNDS OUNCES
______________________________________
DEIONIZED WATER (20.6 gallons)
171 2
PROPYLENE GLYCOL 66 8
DOWANOL PM 59 0
PROPASOL P 113 11
NEOLAN YELLOW Dye *
______________________________________
*1.13 grams
The roller coating of the present invention is produced by mixing:
______________________________________
CHEMICAL POUNDS OUNCES
______________________________________
DEIONIZED WATER (100.1 gallons)
832 11
CITRIC ACID 101 5
DiSODIUM PHOSPHATE 144 12
Dissolve, then add:
14 Be' GUM ARABIC (69.4 gallons)
638 13
GLYCERINE 96' TECH 147 12
NORMAL PROPYL ALCOHOL
29 5
(4.4 gallons)
SCARLET MOO; ACID RED 73
*
______________________________________
*164.13 grams
The plate wash of the universal system is created by mixing:
______________________________________
CHEMICAL POUNDS OUNCES
______________________________________
WATER (74 gallons) 615 12
CITRIC ACID 40 13
Mix until dissolved, then add:
PROPYLENE GLYCOL (14.7 gallons)
110 4
DOWANOL PM 65 8
MAPHOS 8135 16 5
PHOSPHORIC ACID 85% 25 7
ERIO GLAUCINE A SUPRA Dye
*
______________________________________
*2.36 grams
The plate coating of the universal system is created by mixing:
______________________________________
CHEMICAL POUNDS OUNCES
______________________________________
DEIONIZED WATER (25.0 gallons)
208 4
CITRIC ACID 23 1
DISODIUM PHOSPHATE 32 15
14 Be; GUM ARABIC (15.8 gallons)
145 7
MAGNESIUM NITRATE SOLN.
23 11
66%
GLYCERINE 33 10
NORMAL PROPYL ALCOHOL
6 11
(1 gallons)
KITON BLUE Dye *
______________________________________
*0.41 grams
Thus, although there have been described particular embodiments of the
present invention of a universal chemical system for graphic arts
printing, it is not intended that such references be construed as
limitations upon the scope of this invention except as set forth in the
following claims. Further, although there have been described certain
specifications used in the preferred embodiment, it is not intended that
such be construed as limitations upon the scope of this invention, except
as set forth in the following claims.
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